The present invention relates to a device for exchanging heat, in particular for motor vehicles. In air conditioning systems for motor vehicles, electrical heating devices are increasingly used which serve for example to defrost the windshield directly after starting or to heat the passenger compartment.
In the prior art heating systems are known comprising heating elements such as in particular PTC heating elements which heat up due to current flowing through. Metal contact sheets are provided being in electrical connection both with the heating element and a power supply.
In the prior art riveted plug connections are known between the power supply and the contact sheets. However, said riveted plug connections have the disadvantage to offer only a relatively small contact surface between the contact sheet and the plug connection. This in turn will result in relatively high temperatures due to current flowing between the plug connection and the contact sheet.
It is therefore the object of the present invention to improve connection with the contact sheet.
The present invention relates to a device for exchanging heat, in particular for motor vehicles, having at least one first component connected to an electrical power supply, and whose temperature varies dependent on current flowing through the component, and at least one second component comprising at least one first and at least one second part element each of which are at least indirectly conductively connected to the first component, wherein at least one part element comprises a first link plate in particular at one end.
In addition at least one electrical contact means is provided which is conductively connected to the link plate of the at least one part element by means of a first connecting means and serves to connect an electrical power supply, wherein the contact means comprises at least one second connecting means having receiving means for a second link plate.
According to the invention, both of the connecting means comprise at least one flat portion and the first and the second connecting means interlock so as to result in a force-closed connection between the first and the second connecting means by means of at least one clamping means and electrical contact is established at least between a primary surface of the flat portion of said first connecting means and a primary surface of the flat portion of said second connecting means.
Connecting means within the scope of the present invention is understood to mean every means which, by interacting with another connecting means, effects a substantially force-closed connection between the two connecting means. Connecting means may for example include a clamp securing a pin or a plate. Connecting means in the sense of the present invention is also understood to include at least partially meshing or interlocking means.
Electrical contact means is understood to include means designed to establish contact with an electrical power supply.
A flat portion is understood to include a portion forming a surface of specified length and specified width. Such flat portion may be for example the surface of a plate-like component.
In another preferred embodiment at least the receiving means comprises at least one clamping element which results in a form-fitting and/or force-closed connection with at least one link plate.
Clamping element is understood to mean such elements which are biased and comprise at least two portions capable of exercising clamping force on another element.
It is preferred that at least one clamping element urges the flat portions at least of the receiving means and the second link plate against one another and in another preferred embodiment comprises at least one curved portion.
It is particularly preferred that at least the contact means comprises at least two clamping elements.
In another preferred embodiment at least the second link plate is substantially, at least sectionally, surrounded by the receiving means. Substantially surrounded is understood to mean that the surrounding connecting means does not have to continuously surround the surrounded connecting means but it surrounds a specified peripheral portion of the surrounded connecting means which portion is larger than 50%, preferably larger than 60% and particularly preferred larger than 70%.
In another preferred embodiment the first and the second connecting means are pressure-joined with each other such that preferably a form-fitting and/or force-closed connection between the connecting means is established.
In another preferred embodiment at least the contact means consists at least partially of a material selected from a group of materials including copper, brass, in particular but not exclusively tin-plated brass, aluminum, iron and the like.
In another preferred embodiment at least the contact means comprises nickel (Ni) at a percentage between 0.2% and 5%, preferably between 0.5% and 3% and particularly preferred between 0.8% and 1.8%.
It is preferred that at least the contact means comprises silicon (Si) at a percentage between 0.05% and 2%, preferably between 0.1% and 1% and particularly preferred between 0.15% and 0.35%.
In another preferred embodiment at least the contact means comprises phosphorus (P) at a percentage between 0.001% and 1%, preferably between 0.005% and 0.3% and particularly preferred between 0.01% and 0.1%.
It is particularly preferred that at least the contact means comprises nickel at a percentage of 0.8% to 1.8%, silicon at a percentage of 0.15% to 0.35%, phosphorus at a percentage of 0.01% to 0.1% and copper at the balance percentage resulting after subtracting from 100% the portions of nickel, silicon, and phosphorus.
It has been found that the quantities of the individual components mentioned above contribute to guaranteeing reliable functioning of the plug-in connection over a broad temperature range. Thus, reliable operation of the connections within a temperature span ranging at least from −40 degrees centigrade to 130 degrees centigrade is possible where the high temperatures mentioned can occur for example by interaction of high ambient temperature and additional heating-up by electric current.
In another preferred embodiment at least the contact means is at least partially made of brass (CuZn) and particularly preferred of tin-plated brass.
In another preferred embodiment at least the contact means is connected to a cable. Said cable preferably serves to connect the connecting means to a terminal of a power supply. It is preferred that at least the contact means is connected to a control system which controls the current flowing through said first component.
In another preferred embodiment at least one part element of at least one second component is made of a group of materials including copper, brass, in particular but not exclusively tin-plated brass, iron and the like.
It is preferred that said first component comprises at least one heating means selected from a group of heating means comprising PTC heating elements, resistance heating elements, plasma heating elements and the like.
In another preferred embodiment a plurality of first and second part elements is provided in an alternating arrangement, wherein it is preferred that first components are positioned between part elements. Said first and second part elements are preferably contact sheets connected with opposite terminals of a power supply. The alternating arrangement is designed to guarantee that a current flows through the first component which is placed between part elements. Although it is possible to position said first components directly between said first and second part elements, it is preferred to provide between the individual part elements additional, in particular conducting, elements such as corrugated ribs, additional contact sheets and the like.
In another preferred embodiment at least one clamping means is provided between at least the contact means and at least one part element. It is preferred that the link plate at the end of the at least one part element engages with the at least one second clamping means so as to establish a force-closed and/or a form-fitting, detachable connection.
In another preferred embodiment at least one link plate comprises at least a partially rounded and/or beveled surface. Said surface preferably serves to facilitate pushing the respective connecting means into one another.
In another preferred embodiment at least one flat portion comprises at least one electrically conductive, structured sub-section. The latter is preferably structured by surface shapes selected from a group including ridges, fins, naps, holes, recesses, roughening or the like.
In another preferred embodiment the longitudinal directions of the first and the second link plates are substantially parallel relative each other. Coinciding longitudinal directions are also considered parallel in the sense of the present invention. It is preferred that the longitudinal direction of the first end link plate coincides with the longitudinal direction of the part element of the second component.
In another preferred embodiment, in assembled condition the first and the second link plates are twisted at a predetermined angle α relative the longitudinal direction of the link plates. This is to be understood such that the flat portions of the two link plates are twisted relative each other at the predetermined angle. Preferably the angle α is between 0 degrees and 90 degrees, preferred between 0 degrees and 45 degrees and particularly preferred between 0 degrees and 20 degrees. In another preferred embodiment the angle α is approximately 90 degrees.
The method of the invention of manufacturing the device of the invention or a preferred embodiment comprises at least the following steps.
Punching at least one shaped element from a substantially flat sheet, in particular but not exclusively a metal sheet, transferring two shaped elements into at least one first and at least one second component according to the invention using at least one method such as in particular but not exclusively bending.
It is preferred to structure at least one electrically conductive subsection of the receiving means of the invention by shaping the surface in punching and/or in at least one shaping process.
The present invention further relates to applying the device specified above for exchanging heat in an air-conditioning system in particular for motor vehicles.